Making yogurt

I thought I had a post on here about making yogurt at home, but can't find it.  So, here it is.  I usually use 1/2 gallon of Hartzlers milk and any active culture plain yogurt you want to use.  This last time I used an organic greek yogurt to get that kind of sour creamy bite.   We eat the yogurt, but I also use it to wash my hair so, two birds...

Anyhoo, pour your milk of choice (whole, 2%, or skim) into a large, stainless steel, heavy bottomed pot.  Heat it on medium until it looks a bit foamy, but is not boiling in the least.  Turn off the burner and let it cool.  It needs to cool until you can hold you small finger in the milk for 10 seconds.  You will have to experiment with this.  Once it has cooled to the finger degree, put 2 tablespoons (at least, you can add more if you want) of plain yogurt (with active cultures, I used Greek yogurt) to a small bowl.  Add in about the same amount of your cooled milk.  Whisk the two together so they become one.  Pour the lot into the pot and whisk it around to mix them up.  Have 2 clean quart jars ready.  Fill the jars and tighten the lids.  There may be a bit left over, so pour it into another small jar.  Wrap the jars up with a couple of towels.  If it's chilly in your house, add a hot water bottle.  Just put the hot water bottle on top of the jars and wrap the whole thing up with your towels, usually 2 towels.  Wait until tomorrow.  Open a jar and see what you've got.  Usually it's yogurt, with a yogurt consistency.  Sometimes not.  You can still use it for smoothies or hair washing.  There are other steps, like straining out the whey, but I'm not too worried about doing that.  Put the jars in the refrigerator.  All done.  It's so easy and delicious.